Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121138

Area Forecast Discussion
National Weather Service Green Bay WI
538 AM CST Fri Jan 12 2018

Updated aviation portion for 12Z TAF issuance

.SHORT TERM...Today...Tonight...and Saturday
Issued at 351 AM CST Fri Jan 12 2018

Have made some changes to the early part of the forecast, as
clouds have proven to be more persistent than previously thought,
and lake-effect snow showers off Lake Superior have been more
widespread and have pushed farther south than expected. Still
believe that a clearing trend will occur outside of the snowbelt
this morning as strong subsidence and drying commences. This
should also cause lake-effect snow showers to gradually become
less numerous, and to remain closer to Lake Superior. Additional
accumulations of 1-2 inches are possible in northwest Vilas county
by this evening. High temperatures will be roughly 25 to 35
degrees colder than yesterday, with readings only in the single
digits and teens.

Scattered lake effect snow showers will affect Vilas county
tonight, then taper off on Saturday morning. With mostly clear
skies, temperatures will plummet to 10 to 15 below zero over
much of north central and central WI tonight, with wind chills
dropping to 20 to 30 below zero. A wind chill advisory will likely
be needed, but will let the day shift make the final decision on
that. Lows in eastern WI will be mainly in the 5 above to 5 below
zero range, warmest near Lake Michigan. Highs on Saturday should
only reach the single digits to lower teens.

.LONG TERM...Saturday Night Through Thursday
Issued at 351 AM CST Fri Jan 12 2018

Main story for this period will be the frigid weather for the
weekend, snow chances Sunday afternoon into Monday night, the
slight modification of the cold across eastern Wisconsin Monday
into Tuesday, then a moderation in temperatures at the end of
next week.

For Saturday night, high pressure is expected to move from Iowa
into Illinois by sunrise on Sunday morning. It appears there may
be enough of a gradient to keep winds up around 5 mph, thus a
wind chill advisory may be needed for portions of north- central
and far northeast Wisconsin. Low temperatures will range from the
single digits below zero near the Lake Michigan shoreline to near
20 below across portions of north-central Wisconsin. On Sunday,
snow is expected to develop during the afternoon hours, mainly
west of the Highway/Interstate 41 corridor. The snow will
continue through much of Sunday night into Monday night where most
locations could see 2 to 5 inches of snow. The forecast for
Monday afternoon into Monday night becomes much more interesting
as the models indicated a surface trough dropping southward across
eastern Wisconsin Monday night. This feature will be focus for
ongoing snow activity. The models continue to indicate a period
where the low level winds may turn to the east/northeast. If this
does occur, snowfall totals may need to be bumped up across the
Fox Valley/lakeshore region Monday night. Will need to watch this
scenario over the next few days. One benefit of the system Sunday
into Monday night will allow for warmer overnight low temperatures
due to cloud cover. Raised minimum temperatures up a few degrees
for Sunday night and Monday night. The warmest readings will be
found near the Lake Michigan shoreline.

On Tuesday, will continue a small chance of snow showers across
much of the region due to northerly flow off of Lake Superior.
The chances of snow showers will continue across the far north
Tuesday night into Wednesday morning. Otherwise, high pressure
then builds into the region Tuesday night and Wednesday. Wednesday
morning will probably be colder than Monday or Tuesday morning
due to the lack of cloud cover and winds. A moderating trend is
expected at the end of the week. High temperatures by Friday could
warm back into the 20s, if not even some lower 30s.

.AVIATION...for 12Z TAF Issuance
Issued at 531 AM CST Fri Jan 12 2018

Most locations still had MVFR ceilings early this morning, though
partial clearing was occurring in parts of northeast WI. Lake-
effect snow showers were ongoing over north central WI, and were
reaching as far south as the RHI TAF site. Strong subsidence and
low-level drying should lead to more widespread clearing during
the mid to late morning, and cause lake effect snow showers to
retreat to mainly Vilas county. Gusty northwest winds will
continue through the day, then diminish during the late afternoon
and evening.



SHORT TERM.....Kieckbusch
LONG TERM......Eckberg
AVIATION.......Kieckbusch is the U.S. government's official web portal to all federal, state and local government web resources and services.